Conventionally, there are image capturing apparatus, such as electronic cameras, that include, as a recording medium, a memory card with a solid-state memory element, and records and reproduces still images and moving images captured by a solid-state image sensor, such as CCD and CMOS sensors.
Japanese Patent Laid-Open Nos. 2003-244712 and 2009-158800 propose an example of a technique related to the solid-state image sensor mounted on the image capturing apparatus, in which photoelectric conversion units of part or all of a plurality of pixels forming the solid-state image sensor are divided into a plurality of photoelectric conversion parts. Examples of applications of the image sensor include detecting the focus in a pupil division method and generating a 3D image based on output signals obtained from the divided photoelectric conversion parts. Meanwhile, outputs of the divided photoelectric conversion parts can be added pixel by pixel to use the outputs as a normal imaging signal.
However, there is the following problem when the outputs from the divided photoelectric conversion parts are added and used as a normal imaging signal during normal photographing in the solid-state image capturing apparatus.
When pixels including divided photoelectric conversion parts are formed as in Japanese Patent Laid-Open Nos. 2003-244712 and 2009-158800, various pixel constituent elements may be arranged between the plurality of photoelectric conversion parts of the pixels. For example, to increase the areas of the photoelectric conversion parts to improve the sensitivity, it is preferable that a plurality of photoelectric conversion parts share a floating diffusion unit (FD unit) and the like, instead of arranging the FD unit and an output signal line for each photoelectric conversion part. In this case, it is desirable to arrange the FD unit at the center of the plurality of photoelectric conversion parts that share the FD unit. In this way, if pixel constituent elements, such as the FD unit, are arranged between the photoelectric conversion parts, a non-sensitive area exists between the plurality of photoelectric conversion parts of the divided pixels. Even if the constituent elements arranged between the plurality of photoelectric conversion parts are eliminated, it is difficult to totally eliminate gaps between the plurality of photoelectric conversion parts in the pixels due to manufacturing accuracy, alignment accuracy, and the like of the pixel unit.
For this reason, non-sensitive regions of the pixel constituent elements and separation regions that separate the photoelectric conversion parts (hereinafter, collectively called “separation regions”) are necessary between the plurality of photoelectric conversion parts in the pixels. However, when output signals from the plurality of photoelectric conversion parts are added pixel by pixel to use the output signals as one pixel signal, the sensitivity is reduced because of the separation regions, compared to normal pixels in which the photoelectric conversion units are not divided.
Since the separation regions are non-sensitive, the luminous flux that reaches the separation regions is not outputted as the signal. However, the state of the photographing lens, the aperture value, the angle of incident light, and the like change the amount of light reaching the separation regions relative to the amount of light received by the imaging pixels, which causes the output signal to depend on the aperture, the angle of incidence, and the like.
Japanese Patent Laid-Open No. 2009-158800 also proposes a method of forming a space above the photoelectric conversion parts of a pixel to separate the incident light to the divided photoelectric conversion parts. However, the space arranged above the photoelectric conversion parts of a pixel is also a separation region. Therefore, compared to when the pixels are not divided, the sensitivity is reduced, and the characteristics of the angle of incidence are degraded.